In some parts of the world, buildings are subject to high winds or seismic events or both. In the United States, high winds and seismic events are particularly prevalent in California, near the coast along the Gulf of Mexico and in parts of the east coast. The forces produced by winds and earthquakes subject buildings and their roof framing systems to extreme lateral loads.
It is vital in the design of buildings in these areas, particularly in configuring their framing systems, which include the top chords of large truss systems and girders, to reduce the forces on the frame elements caused by these excessive lateral loads on a deck system supported by the building's framing system.